Method and system for characterizing an optical device

An embodiment of the invention relates to a system comprising an optical device (10) and an evaluation device (20) for characterizing the optical device. The optical device comprising a 90° optical hybrid unit (30) having a first and second optical input (30E1, 30E2) and at least two optical outputs (30A1-30A4) wherein optical output signals (So1-So4) leaving the optical outputs have optical phase differences between each other of 90° or multiple thereof; a first photodetector (P1) connected to a first optical output (30A1) and a second photodetector (P2) connected to a second optical output (30A2), wherein the first optical output emits a first optical output signal (So1) and the second optical output emits a second optical output signal (So2), said second optical output signal having an optical phase difference of 180° relative to the first optical output signal; and a first transimpedance amplifier (Tr1) connected to the first and second photodetectors (P1, P2). The evaluation device (20) is characterized by a signal source (110) configured to generate a first and second intensity-modulated optical input signal (Sin1, Sin2); an optical phase shifter (120) adapted to phase-shift the optical phase of the second intensity-modulated optical input signal relative to the optical phase of the first intensity-modulated optical input signal; a measurement unit (160) adapted to measure the electrical output signal of the first transimpedance amplifier (Tr1); and a control unit (130) adapted to control the optical phase shifter.